1. Field of the Invention
This invention relates to a bioreactor carrier for use as a carrier to which animal cells, plant cells, microorganisms and/or protozoans are fixed to obtain a bioreactor for substance production, harmful substance treatment, waste oil treatment, wastewater treatment, deodorization and the like, and to a method of treating wastewater using the carrier.
2. Description of the Background Art
The carriers used in bioreactors are of two types: porous and gel (nonporous).
Porous carriers include those made of polyurethane, cellulose, polypropylene, polyvinyl formal and ceramic.
The porosity of these carriers gives them a large surface area. They are frequently used with animal cells, plant cells and/or microorganisms fixed to their porous surfaces.
Gel carriers include those made of polyurethane, polyethylene glycol, polyvinyl alcohol, polyacrylamide and alginic acid.
Although these gel carriers are generally used with animal cells, plant cells and/or microorganisms fixed by envelopment within the gel, they can also be used with animal cells, plant cells and/or microorganisms fixed to the gel surface.
Both the porous carrier and the gel carrier improve bioreactor treatment performance by retaining large numbers of the desired animal cells, plant cells and/or microorganisms. Their effect is consequently limited during startup, i.e., until the animal cells, plant cells and/or microorganisms have adhered to the carrier.
A preculture period is therefore particularly necessary when using slow-breeding animal and plant cells and/or autotrophic microorganisms.
Animal cell, plant cell and/or microorganism growth is also adversely affected when the nutrient environment in the bioreactor deviates from the optimum one for proliferation of the desired animal cells, plant cells and/or microorganisms.
Japanese Patent Application Laid-open Nos. 3-258398 and 4-320685 and Japanese Patent Application No. 8-139723, for example, teach that selective retention of desired animal cells, plant cells and/or microorganisms can be achieved by enveloping the cells and/or microorganisms in the carrier at the time it is produced. However, the production, storage and transport of the disclosed carriers must be conducted under restrictions regarding temperature, humidity, oxygen exposure and the like so as not to adversely affect microorganism growth.
As explained in the foregoing, one or the other of two ways must be used to secure preferential growth and proliferation of desired animal cells, plant cells and/or microorganisms at the surface or interior of the carrier. One is to use some method to envelop the microorganisms within, or adhere them to the surface of, the carrier in advance. The other is to culture them for whatever time necessary in a culture medium whose nutrient conditions have been optimized for the desired microorganisms. The invention is directed to overcoming the foregoing problems.